What 11 Billion People Mean for Sanitation

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Editor's note:By the end of
this century, Earth may be home to 11 billion people, the United
Nations has estimated, earlier than previously expected. As part
of a week-long series, LiveScience is exploring what reaching
this population milestone might mean for our planet, from our
ability to feed that many people to our impact on the other
species that call Earth home to our efforts to land on other
planets. Check
back here each day for the next installment.

Hong Kong, a city of 7 million inhabitants, faces a major garbage
crisis. The region's three landfills are expected to fill up
completely by 2020, and even if recycling increases, the country
will have to expand its landfills to deal with the thousands of
tons of waste generated every day, officials say.

"Hong Kong currently solely relies on landfills to dispose of its
municipal solid waste, which is not a sustainable way to treat
waste," said a spokesman for Hong Kong's Environmental Protection
Department.

Hong Kong and its overflowing landfills are not alone. In fact,
the planet as a whole faces a serious problem: what to do with
the tons and tons of garbage, poop and other waste humans
generate, especially with the population set to grow considerably
this century.

A recent statistical analysis predicts the world
population will hit 11 billion by the year 2100, outpacing
United Nations estimates. By then, these piles of rubbish and
other waste may become insurmountable.

Today, as an example, the world has about 3 billion urban
residents, who generate 2.6 lbs. (1.2 kilograms) of municipal
solid waste per person per day, a World Bank report estimates.
That adds up to about 1.4 billion tons per year. [ What
11 Billion People Means for the Planet ]

By 2025, as a result of economic development and urbanization,
that number will climb to 4.3 billion urban residents generating
2.4 billion tons of waste per year, the report estimates. Where
will it all go?

Some countries may run out of space to put all that waste,
meaning the rubbish could end up in the oceans. Experts say
people will have to find ways to recycle more and to generate
energy from these waste streams if they're to have any hope of
managing the issue.

"Even if the population were stable, we already have a serious
problem," said Barbara Evans, a civil and environmental engineer
at the University of Leeds, in England.

Dealing with the world's trash

Waste management varies widely from country to country. Larger
countries can afford to create more landfills, but must also find
ways to recycle more. Meanwhile, smaller countries face a more
urgent risk of running out of landfill space.

"The current situation with solid waste is a bit of a
checkerboard," said Sara Bixby, deputy executive director of the
Solid Waste Association of North America. Europe, the United
States and Australia are focusing on managing waste and lessening
its environmental impact, but in many developing nations, rapid
urbanization is outstripping waste management infrastructure, she
said.

In 2011, the United States generated about 250 million tons (227
million metric tons) of trash, according to the Environmental
Protection Agency. Just over half of that
garbage went to landfills, about a third was recycled,
and the remainder was burned to generate energy.

While the average size of U.S. landfills has increased over the
years, their number has decreased. From 1990 to 2011, the total
amount of waste going to landfills dropped by more than 11
million tons — from 145.3 million to 134.2 million tons. Despite
producing one of the highest levels of solid waste per capita,
the continental United States has enough open space for landfills
in the foreseeable future.

The situation in smaller countries and areas is strikingly
different. In Hong Kong, where landfills could fill up by 2020,
the government is pursuing an aggressive recycling goal. But Hong
Kong Environmental Protection Department officials told
LiveScience that "landfills are an essential part of the waste
management chain, as even with the best efforts in waste
reduction and recycling, there is still a need to landfill wastes
that cannot be recycled or treated."

And not all waste is created equal: Plastic is one of the worst
offenders, because it takes so long to degrade. An unsettling
amount winds up in the ocean, contributing to the Great
Pacific Garbage Patch, a region of swirling marine debris in
the central North Pacific Ocean. "We can't look at the ocean as
just a liquid landfill," Bixby told LiveScience. Marine animals
can ingest or become tangled in trash, and toxic waste can poison
ecosystems.

Rather than simply finding more places to dump trash, the world
should look for a way to decrease its need for landfills, Bixby
said. But trash isn't the only kind of waste humans generate —
there's human waste, also. And many parts of the developing world
don't have basic sanitation facilities, making the issue even
more urgent in those locations.

West Africa had an unusually severe rainy season in 2012, causing
flooding in the slums of Sierra Leone and Guinea. The latrines in
those countries weren't built to withstand so much water and
overflowed, bringing on an epidemic of cholera, a diarrheal
disease that spreads through contact with contaminated feces. The
news agency IRIN News reported that the disease killed about 400
people and sickened more than 25,000 others.

Eleven billion people will produce a heap of
human waste. Even now, rather than being treated and
sent out into the ecosystem as environmentally safe waste fluid,
much of the poop just piles up in inhabited areas. That's
because, currently, about 2.6 billion people (35 percent of the
world's population) live without access to basic sanitation. They
don't have working toilets, or even a pit latrine, let alone
sewage treatment plants. Many of these people live in developing
countries, where most of the population growth is expected to
occur. [ 5
Ways Toilets Change the World ]

As in the case of Sierra Leone and Guinea,
insufficient sanitation poses a serious threat to public
health. Without proper toilet facilities, people are forced to
defecate in the open, near rivers or living areas. In India,
290,000 gallons (1.1 million liters) of raw sewage get dumped
into the Ganges River every minute, according to the World Health
Organization.

Currently, poor sanitation "contributes to two of the three
leading causes for preventable death for children under five,"
said Lisa Schectman, head of policy at the NGO WaterAid America.
Human waste can contaminate the water supply, leading to
diarrheal diseases like cholera, which many people suffer from
chronically, Schectman said. These diseases cause malnourishment,
low birth weight and cognitive problems. Poor sanitation also
increases the risk of ingesting fecal matter, which can lead to
stunted growth.

A fly that breeds exclusively on human excrement carries the
disease called
trachoma, the leading cause of preventable blindness. Feces
can also contaminate soil, breeding parasitic worms like
roundworm and hookworm that cause delays in brain development in
children and serious intestinal blockages or even death in
adults.

In the course of her work, Schectman has visited places with dire
sanitation needs. "You would see ramshackle buildings. You'd see
a concentration of flies. It might smell, particularly in hot
climates. Sometimes you would see an open pit, especially in
rural areas. In Bangladesh, during the rainy season, you may see
sludge running down the streets," she told LiveScience.

Aside from health, lack of sanitation facilities is complicated
by cultural mores and limits access to education. And the
problems will only become more widespread as the population
grows.

"An increasing population means increased human waste, and
government provisions are not keeping up," Schectman said.

Culture and urbanization

Complicating the world's ability to deal with physical waste
itself, discussing toilet matters is culturally taboo in some
places, especially among women. "For
women to discuss their bodily functions is considered
completely out of the realm of possibility in many cultures,"
Schectman said. Women who lack toilet facilities must travel
farther away to relieve themselves, putting them at risk for
sexual violence. And many girls in developing countries drop out
of school because they have no private restroom.

Public toilet blocks were advocated as a solution to the problem,
but a study of such blocks in Bhopal, India, in November 2008
found that men were twice as likely as women to use them. Many
women prefer to use "flying toilets" — basically plastic bags
inside their homes — so they don't have to go outside at night.

The population uptick means more and more women will face these
cultural dilemmas. A lack of sanitation facilities will keep more
young women out of school, creating a wider education gap,
Schectman said.

Further, the world population is not only growing, it's becoming
more urbanized, placing a larger load on the systems that do
exist. Cities need networks for removing waste, whether these are
pipes or trucks or even handcarts. In places like Africa, a
growing population means many people will live on the margins of
formal cities, ignored by the political system.

"Sanitation is a highly politicized topic," said Evans, of Leeds
University. "If you want systems to work well, you need to plan
them in advance." Marginalized people lack the money and clout to
build these systems for themselves. They need politicians to
lobby for better infrastructure. If there's no economic
development, a growing population could make sanitation problems
exponentially worse, Evans said.

First-world problems

Developed countries have sanitation problems of their own. In
Europe, most of the sewage treatment works were built before
people understood biology. These systems were designed to remove
organic matter, not microbes, said Sandy Cairncross, a public
health engineer at the London School of Hygiene & Tropical
Medicine in England. (Organic matter consists of anything
containing carbon, whereas microbes are living organisms that can
make people sick.) [ Managing
the World's Waste (Infographic) ]

It wasn't until about 10 years ago that the European Union
introduced standards of
sanitation in terms of bacteria. Until recently, the city of
Brussels dumped all of its sewage into the river Senne (or
Zenne). But starting in 2000, the city began building water
treatment plants to limit the amount of sewage that goes into the
river.

Then there's the problem of expense. In the developed world,
installing plumbing and sewers costs hundreds, if not thousands,
of dollars, Cairncross said. As the urban population grows, it
"means spending a lot of money in a hurry that isn't there," he
said.

Climate change is further exacerbating the problems of managing a
growing population's waste. Global warming is decreasing the snow
and ice cover on mountains, which feeds rivers that supply cities
with water for sewers. "Diminishing snow cover means many rivers
that feed cities to flush sewers are not going to have much water
in the dry season," Cairncross said.

Over the past 50 years, rainfall has been declining and becoming
more seasonal in many cities, he said. At least one city in
Australia has a desalination plant to get fresh water, and London
is talking about putting one in, he said.

On the other hand, extreme weather, partly linked to climate
change, will cause a greater risk of flooding in coastal cities.
Flooding can wreak havoc on sanitation systems, like that seen
during the 2012 cholera epidemic in Sierra Leone and Guinea.

Reduce, reuse, recycle

One promising option for dealing with the world's waste problems
involves recovering materials or energy from all that refuse.

Some European countries have already stepped up recycling
efforts. The United Kingdom has a landfill tax on waste that
must be buried in the ground, and the country's total amount of
landfill waste has dropped from about 110 million tons in 1997, a
year after the tax was implemented, to about 45 million tons in
2012. Germany requires its citizens to separate all their waste
and recyclables. And in the United States, about a third of waste
is recycled, much of which is processed in China.

There's also potential to generate
energy and resources from waste. Sweden, for instance, has
launched a successful program for converting garbage into
renewable energy. Only 4 percent of Swedish household waste gets
landfilled. The country created its first waste incineration
plants in the 1940s, and today the process is so efficient that
Sweden has begun importing trash from other countries that pay
for the service.

But solid waste isn't the only valuable kind of waste.

Wastewater contains about 10 times the amount of energy — in
biochemical form — as that needed to treat the water, according
to Barry Liner, director of the Water Science & Engineering
Center at the not-for-profit Water Environment Federation. The
excess energy in biological waste could be fed back to the power
grid, and some companies are already doing this.

Microbes can digest biowaste and turn it into natural gas. In
addition, water can be
reclaimed for drinking, and nutrients such as nitrogen and
phosphorus can be recovered for agricultural use. These systems
are easier to implement in developed countries, Liner said, but
they could also exist on a smaller scale elsewhere.

"If we're truly going to stay ahead of population growth, we're
going to have to change the way we think," Bixby said.

Future of waste

There are reasons to be optimistic that the world can make the
changes it needs to, based on changes that are already occurring.

One of the
Millennium Development Goals, a set of
eight international development goals established
following the Millennium Summit of the United
Nations in 2000, was to provide sanitation to 75 percent of
the world by 2015. Currently, the world has reached 67 percent,
said Liner, who is cautiously optimistic. "While we're not
meeting the Millennium Development Goals in total, there is a lot
of hope," he said.

The world partially achieved these goals by implementing
decentralized systems such as shared latrines in urban areas.
Small-scale systems are much less expensive than sewers and
centralized wastewater facilities, Liner said.

Some organizations are trying to find ways to make sanitation
facilities available off the grid. For example, the Bill and
Melinda Gates Foundation's Reinvent the Toilet Challenge aims to
develop sanitary waterless toilets that don't need a sewer
connection or electricity, and cost less than five cents per user
per day. The foundation has awarded grants to researchers
worldwide to develop engineering solutions for human waste
management, from solar-powered toilets to ones that recover and
purify wastewater.

These kinds of efforts must be expanded if the world is to meet
remaining sanitation needs, Liner and others say.

As Evans said, "We've got the opportunity today, if we take it,
to put ourselves on the right path."